With a few exceptions, it's often hard to identify the right bug by the damage they do and correctly give you an action to take. Best would be to go out at night with a flashlight and take a look when they are feeding. You may have to make more than one trip after dark, but trust me, you can be very surprised in the activity after dark in your garden. There's 'stuff' in my own I never dreamed was there, and no wonder the slug deterrents I'd put out weren't helping when I had climbing cutworms :) Let us know....

I suggest taking a sample of the damage to your local nursery. The gardening experts there might be able to tell you what the pest problem is based on the physical damage. The articles below might help too.

Here is a link that might be useful: Garden-Ideas Garden problems and pests

I recently had the same (or similar) issue with my Gerbera Daisy. I believe it was a green cutworm. It ate my entire plant in a matter of two weeks and left a mess of black droppings that would surround the plant and remain on the leafs.

Just one or two cutworms or caterpillars can cause an amazing amount of damage. An easy and free way to resolve the problem is as above, go out after dark with a flashlight and your oldest pruners, snip in half.